1. Field of the Invention
This invention relates to a leg unit used for support of the body of an electric machine such as a washing machine and, more particularly, to an anti-vibration leg unit which comprises a fixed leg attached to an electric machine body and an elastic leg made of elastic material and assembled to the fixed leg.
2. Description of the Prior Art
A conventional anti-vibration leg unit is disclosed in Japanese Published Unexamined patent application Ser. No. 140866/1978.
This conventional leg unit, as shown in FIG. 11, comprises a fixed leg 52 attached to the bottom of an electric machine body 51 of such an electric machine as a washing machine and an elastic leg 53 assembled to the fixed leg 52. The leg unit has as one of its features a contact surface of the fixed leg 52 with the elastic leg 53, and the fixed leg has a convex portion 54 and a concave portion 55. These convex portion 54 and concave portion 55 define an always contacting portion and another portion which is put into contact when a heavy load is imposed, respectively.
That is, under a light load, for example, while the washing machine is dewatering, the vibration and noise of the machine body 51 are prevented from being trasferred to the floor by virtue of a membranous vibration of a portion of the elastic leg 53 between the outer diameter d of the convex portion 54 of the fixed leg 52 and the inner diameter D of a floor-contacting portion of the elastic leg 53.
Under a heavy load, however, while the washing machine is washing, the elastic leg 53 deflects as illustrated by the dotted lines (see FIG. 11) to come into contact with the concave portion 55 of the fixed leg 52, so that a certain strength is preserved and maintained.
According to the foregoing conventional leg unit, the stiffness of the elastic leg 53 must be enhanced to prevent the collapse of the elastic leg 53 that would occur when a heavy load is imposed; on the other hand, in order to exert sufficient vibration-proof effect, the elastic leg 53 must be made as soft as possible; therefore it is difficult to find a "happy medium" and make an adjustment between these two requirements.
In order to solve the above problem, a vibration-proof leg unit has proposed wherein a flange is disposed on an undersurface of an elastic leg to prevent collapse of the elastic leg caused by heavy load (Japanese Published Examined patent application Ser. No. 36786/1973).
As shown in FIGS.12 and 13, this leg unit comprises a metal leg 62 attached to a bottom of an outer frame 61 of a drum-type washing machine and a rubber leg 63 which has a flange 63a at its under edge and supports the metal leg 62, and the rubber leg 63 is combined with the metal leg 62 with a threaded shaft 64 and the height of the metal leg 62 can be adjusted by operating a lock nut 65.
However, when the above leg unit is used in a manner such as shown in FIG. 12 (when the floor is relatively rigid) or FIG. 13 (when the floor is relatively flexible), in any case it is difficult to prevent the outer frame 61 from vibration, because the undersurface of the flange 63a of the rubber leg 63 is in contact with the floor surface, and the contact area between the flange and the floor is larger, the vibration-absorbing ability of the rubber leg 63 decreases, in particular under a light load, for example in dewatering wherein the dewatering tub along with the washing rotate at a higher speed.